p-Xylene is a raw material for terephthalic acid, which is an intermediate material for polyester, and the like, and important as a basic chemical product in the chemical industry. p-Xylene is industrially produced using as a raw material a fossil resource such as petroleum or natural gas. Industrial production of terephthalic acid from p-xylene is carried out by, for example, air oxidation in an acetic acid solvent by using acetic acid salts of cobalt and manganese as catalysts and sodium bromide as a promoter (Non-patent Document 1).
Similarly to p-xylene, p-tolualdehyde is a useful chemical product that can be converted into terephthalic acid. Production of terephthalic acid from p-tolualdehyde can be carried out by, for example, a method similar to the above-mentioned air oxidation that uses p-xylene as a raw material (Patent Document 1).
Recently, on the other hand, depletion of oil resources, and global warming due to greenhouse gases such as carbon dioxide generated from fossil resources are becoming serious. Therefore, in order to achieve switching to a sustainable, recycling-oriented society, techniques for producing chemical products from substances derived from biomass resources, which are renewable resources, need to be constructed urgently.
In the chemical industry, switching of raw materials from fossil resources to biomass resources is being intensively studied. Among such studies, in order to replace raw materials for terephthalic acid, and eventually raw materials for polyester, with a biomass resource-derived substance(s), methods for producing p-xylene from a biomass resource-derived substance are being studied. For example, Non-patent Document 2 discloses a method for producing a hydrocarbon including p-xylene by a chemical conversion step using as a raw material ethanol, which can be produced from a biomass resource, and a zeolite catalyst. Patent Document 2 discloses a method for producing p-xylene by the chemical conversion steps of dehydration, dimerization and cyclization-dehydrogenation, using as a raw material isobutanol obtained from a biomass resource. Non-patent Document 3 discloses a method for producing p-xylene by the chemical conversion steps of cyclization, oxidization, dehydration and decarboxylation, using as raw materials 2,5-dimethylfuran and acrolein derived from biomass resource-derived substances.